Shutter



June 20, 1944.

H. c. DECKEL ETAL SHUTTER 3 shetsa-sheet 1 Filed Jan. 8; 1941 Invehfors-Y CZOL M 621L071??- By Wan/z Jazz/er- W 1 "flair xflforn eys.

June 1944- H. c. DECKEL EIAL 2,351,932

- SHUTTER .Filed Jan. 8, 1941 f 3 Sheets- Sheet 2 Izna c2 lkiuaradMaura?" I By Zawr nvenfors June20, 1944. c. DECKEL E 2,351,932'

- SHUTTER Fil'ed Jan. 8, 1941 3 Sheets-Sheet 5 I mien fors G. 1m af M mger BY 17-4702 fag/0r Mme?- imam Patented June 20, 1944 SHUTTER Hans C.Deekel, Munich-Solln, and Eduard Maurerand Franz Xaver Stiimmer, Munich,Germany; vested in the Alien Property Custodian Application January 8,1941, Serial No. 373,640

In Germany January 8, 1940 t 11 Claims.

The present invention relates to a process for taking photographs.

With the photographic shutters heretofore known to the art the passageof light is controlled e. g. by swinging shutter-leaves, slidingcurtains and the like; all these means, however,

require complicated actuating devices.

One object of the invention is to provide two polarizing filtersrelatively movable in relation to oneanother to control the passage oflight when taking photographs. E. g. the actuation of a shutter" isfacilitated thereby in the simplest manner.

Another object of the invention consists in the amount of the relativerotatory displacement of the polarizing filters in relation to oneanother being changeable at will.

A further object is that in the case of one stationary and one movablepolarizing filter being used to control the passage of light, bothfilters may be rotated jointly into any desired position, and that thefilter which is stationaryv during the exposure, can be fixed in theposition named.

Finally further objects of the invention consist in one or both of thepolarizing filters serving to control the passage of light being able tobe formed square or as circular discs, rings or ring-sectors.

The form of filter most convenient for every individual case depends onthe arrangement of same. Thus with a photographic camera one filter maye. g. be arranged stationary in the space in front of the sensitivelayer and have a square form, whilst the second movable filter isarranged near the camera lens and has the form of a circular disc.

To these and other ends the invention resides in certain improvementsand combinations of parts all as will be hereinafter more -fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawings:

Figs. 1 to 4 are diagrammatic illustrations of diiferently formedpolarizing-filters which in accordance with the present invention may bemoved in diiferent ways in relation to one another to obtain thecontrolling effect of a photographic shutter.

Fig. 5 is a view showing a shutter constructed in accordance with thecharacteristics of the present invention, the individual parts of itbeing in position of rest;

Fig. 6 is a view similar to that of Fig. 5 with the individual parts ina position corresponding to the shutter under tension.

Fig. 7 is likewise a view similar to that of Fig. 5 with the individualparts in a position corresponding to the shutter when opened.

Fig. 8' is a view similar to that of Fig. 5 with the individual parts inthe closed position subsequent to the openingof the shutter;

Fig. 9 is a partial view similar to that of Fig. 5, constructed inaccordance with the present invention with an exposure regulatingmechanism arranged additionally.

Fig. 10 is a view illustrating a shutter constructed in accordance withthe characteristics of the present invention and with which the amountof the relative movement of the polarizing-filters in relation to oneanother is changeable at will and in which furthermore the parts are inposition of rest.

Fig. 11 is an end elevation with parts of such a shutter being shown invertical-section.

Fig. 12 is a. view similar to that of Fig. 10 with the individual partsin a position corresponding to the shutter under tension.

Fig. 13 is a view similar to that of Fig. 10 with the individual partsin a position corresponding to the position of the shutter when runningdown.

Fig. 14 is a view similar to that of Fig. 13, but with an exposure valueadjusted difierently.

Fig. 15 is a view representing a shutter constructed in accordance withthe characteristics of the present invention and with which the shut teras a whole is rotatably adjustable about the optical axis of thephotographic camera, and in which furthermore the parts are in positionof rest.

Fig. 16 is a partial view-similar to that of Fig. 15, in whichindividual parts occupy a differential position.

Fig. 17 is a partial view in direction of the arrow inserted in Fig. 15with the individual parts on a large scale; and

Fig. 18 is a view similar to that of Fig. 15 with the individual partsin a position corresponding to the position of the shutter when open.

It is a physical phenomenon known in itself that the path of rays oflight may be controlled by means of two polarizing-filters changeable intheir reciprocal angular adjustment; this control is possible due to thefact that the electromagnetic waves of the light which are polarizedafter having passed through the first filter, that is to say which canno longer swing but in one definite plane, cannot pass through a secondfilter unless its individual structural parts are parallel orapproximately parallel to the structural parts of the first filter. If,however, the structural parts performs B of the two filters lie at acorresponding angle e. g. at right angle to one another, any passage ofthe light polarized in the first filter through the second filter isimpossible. According to the present invention this possibility ofcontrol resulting from the wave-like nature of the light was the baseior the construction of a photographic shutter.

In Figures 1 to 4 several arrangements of polarizing filters acting asshutters are shown the individual filters or which may be moved indiflerent ways to admit or to impede the passage of rays of lightrespectively. I

With the arrangement according to Fig, 1, two polarizing filters I and 3are arranged in such a manner in a photographic camera not shown thattheir axes of rotation I and I coincide with the optical axis or theapparatus. with this arrangement a control of light in the sense or theinvention may be achieved e. g. by making the one filter (l) stationary,while the other filter (I) is rotatably adjusted forward and backward inrelation to the former (I) in its plane about the axis 5 by 90; insteadof this the filter I might also be rotatably adjusted in the samedirection twice by 90 in relation to the other filter and onlysubsequently returned to its original position. This return-movement maye. g. again be executed in two rotations by 90 each in relation to thestationary filter (this resulting at the same time in a new working stepof the shutter) or filter 3 which is immovable during the precedins stepis rotatably adjusted by 180 jointly with filter I, the shutter thusremaining closed durin the return-movement (closed winding up).Naturally, the return-movement may be effected iorwards or backwards;hence results as a special case a shutter in which the movable filter(I) continuous rotation by 90 each.

Instead of one movable and one stationary polarizing filter also bothfilters I and I can be movable and be rotated simultaneously against oneanother about the axes I and I to control the passage of light, thepossibilities of movement being the same as indicated above, and theonly difference consisting in the angles of rotation being half aslarge.

A further possibility oi performing the movements of the filters tocontrol the passage of light is given with the arrangement according toFig. 1, by e. g. filter I being rotatably adjusted by 90 in relation tothe stationary filter 8 and thereupon filter a hurrying 'aiter filter Iwhich is now at rest,'by the same degree of angle. For thereturn-movement the same possibilities indicated I above exist also inthis case.

Finally it would also be possible to rotatabLy adjust both the filtersalternately by 90 each in relation to each other (thus in directionsremaining constant).

In Fig. 2 an arrangement of filters is shown with which a filter II canswing about an axis II lying outside the optical axis 9 and at rightangle to the latter. The second filter u is supported stationary in thephotographic camera. with this arrangement the passage or light iscontrolled by filter I I being swung out of the path of rays to allowthe .light to pass through; to

interrupt the passage of light filter II is thereupon swung back againto its original position shown in Fig. 2. Naturally also filter I4 mightbe supported swingable by a second axis lying parallel to axis II. theopening and closing or the passage or light beins the two filters I Iand Il Jointly. Besides it would a,ss1,ess

also be possible to swing one or both the filters about axes cutting theoptical axis 9; in this case one filter or both of them might be swungby 90 each to control the passage of light.

' the camera lens IS. The arrangement might also be made in such a waythat but one of the two filters is constructed swingable whilst theother filter lies stationary in front of the camera lens I9; the area ofthe stationary filter may then be limited to the aperture of the cameralens.

With polarizing filters having their axes of rotation outside the opticaxis of the camera the same relative movements are possible to controlthe passage of light in itself as enumerated in connection withtheexample of execution according to Fig. l, the only difierence consistingin the filters illustrated e. g. in Fig. 1 are always executing merelypure rotations as self-motions. whilst with the arrangements accordingto Figs.

2-4 a swinging of the filters takes place. These swinging self-motionsof the filter or filters respectively render it possible that the freepassage of light may also be effected in such a way that one filter orboth (contrary to the rotating filters which cover each other in everyposition) are partially or entirely removed from the path of rays. Whenreleasing the passage of light by removal of one filter or of both ofthem, the distance of the axes of rotation of the filters from theoptical axis may be chosen at will. thus also infinitely large; in thelatter case the swinging motions of the filter or filters would becomeparallel displacements.

The polarizing filters shown in Figs. 1 to 4 may be arranged singly orjointly immediately at-the camera lens or/and between the lens and thelight sensitive surface.

In Figs. 5 to 9 an example of execution of a photographic shutteraccording to the invention is shown where the axes of the two polarizinfilters drawn for reasons of greater clearness with different diameterscoincide with the optical axis of the photographic camera.

The shutter consists of two disc-like polarizing filters 20 and 22 whichare supported rotatably about their joint middle axis 24 at acorresponding distance and covering one another in a photographic cameranot shown. The filters carry stops 20 and. 28 which are engaged when theshutter is in the position of rest (Fig. 5) by pawls 30 and 32 supportedrotatably at the places 34 and 38; by these pawls the filters 20 and 22are safeguarded against displacement in their position of rest in whichno light can reach the emulsion-carrier due to the reciprocalangleelected by swingin position of the structures of their material.Furthermore a master member 38 having the same axis as the two filtersand carrying a setting lever 40 is supported rotatably. Said settinglever adjoins in theposition shown in Fig. 5 with its one side formedaccordingly two stops 42 and it provided at the circumference of filters20 and 22 respectively. The ends oi two tension springs 45 and 48 aswell as of a retracting spring 50 are also fastened to the setting lever40. The springs 40 and as are anchored with their other ends in thefilters 20 and 22 at 52 and 54, whilst the secexpansion of springs 46,48 and 60 adjusted by rotation by an angle of 90 in a clockwisedirection into the position shown inFig. 6 and it is held there inposition by a pawl 60 activated by a spring; during this motion 01'tension the filters 20 and 22 are held by the pawls 30 and 32 in theiroriginal position impeding the passage of light. When the release lever62 arranged at the pawl-lever 30 is pressed down against the action ofits spring 64, the pawl 30 is lifted thereby out from the notch 26;thuspfilter 20 is released and vthe force of the tensioned spring 46displaces same rotatably towards the right, until. stop 42 comes againto adjoin the setting lever 40 (Fig. 7). Corresponding to the path oftension of lever 40 the angle of displacement by rotation of the filteramounts to 90 in doing so. By this rotatory displacement of the onefilter against the other one which is still held in its position by pawl32, the passage of light to the emulsion carrier is released so that theshutter is open in the position shown in Fig. 7. Shortly before filter20 completes its opening movement, the stop 26 provided on it reaches anarm 66 of pawl 32 and imparts both of them a short rotation to the leftagainst the action of a spring 60; thus stop 28 is released and now thesecond filter moved by the force of spring 48 hurries after the firstfilter, until stop 44 comes to adjoin lever 40 which likewisecorresponds to an angle of rotation of 90". Thus both the springs 46 and48 are released, and the reciprocal position of the filters being thesame now as in Fig. 5, the shutter is closed again (Fig.8).

So as to bring the entire set back again to the position of rest shownin Fig. 5 automatically and without opening the shutter, the filter disc22 carries a stop 10. When ending the closing movement, this stopencounters an arm I2 of pawl 60 and displaces both against the force ofspring 58 in such a way that pawl 60 i lifted out from its notch at thesetting lever 40. Thus the force of the retracting spring 50 comes intoeffect and turns the setting lever 40 or the master member 38respectively and with same over the stops 42 and 44 also the twopolarizing filters jointly towards the left, until the notches 26 and 28have passed under the evading pawls 30- and 32, and are back again inthe position shown in Fig. 5. Any rotation of the filters'towards theleft beyond these positions of rest is prevented by stop I4.

In Fig. 9 the shutter described above is shown with an exposureregulating mechanism of known kind arranged additionally for executingexposures of difierent durations. This exposureregulating mechanism 80is supported in a suitable manner in the shutter casing and is impelledby a lever 82 protruding into the path of an arm 84; this arm forms partof the mu'ltiple-arm-lever I2, 86 supported in the point of rotation 36.This device is acting in the following manner:

After actuating the release lever 62 the filter- 20 is displaced byrotation by force of spring in a clockwise direction in the manneralready described. The stop 26 moved with it by this action encountersshortly before ending this rotatory movement the arm 66 and attempts torotate the latter and the levers connected with it about point 26. Thisrotatory displacement, however, is delayed by the exposure regulatingmechanism 80, so that the release of the stop 28 by pawl 32 and thus thebeginning of the closing movement of the second filter begins onlyafter. a certain time. The amount of this delay determining the durationof exposure may be determined at will in known manner by correspondingadjustment of the exposure regulating mechanism. The return oi theexposure regulating mechanism to the position of rest determined by astop 86 is effected by a tension spring 88.

It may still be mentioned that it is, of course, possible withoutdifllculty to intercalate between the release lever 62 and the pawl 30 aretarding device of known construction. 7

Building in an exposure regulating mechanism in a shutter naturallyinvolves the shutter being made more complicated and more expensive. Soas 'to avoid these drawbacks a shutter may be used as shown in Figs. 10to 14 of the drawings. With the shutter shown in these figures exposuresmay be effected which had so far only been possible by producingdifferent speeds of running down, without interfering with the speed ofrunning down of its moved parts, that is to say without using adjustableexposure regulating mechanisms or the like. This effect is produced bytaking advantage of the wellknown physical fact, that the amount of thelight allowed to pass through is dependent on the mutual position of twopolarizing filters at the time.

According to Fig. 10 two disc-shaped polarizing filters 90 and 92 arearranged at a corresponding axial distance and covering one another in aphotographic camera not shown, their common middle axis 94 coincidingwith the optical axis of the photographic camera. Furthermore thearrangement of the two filters is suclrthat filter 90 may berotatedabout axis 94, whilst the filter 92 is supported not rotatably in thephotographic i camera. For the purpose of its displacement by rotationthe filter 90 is held in a ring-shaped mounting 96 which shows at itscircumference two adjoined pieces 98 and I00. Adjoined piece I00 isengaged by a tension spring I02 and tends to rotate mounting 96 andconsequently filter 80 in a clockwise direction, until adjoined pieceI00 comes to adjoin a stop I04 (Fig. 10). In a position shown in Fig. 11a rotatable master mem.- ber I06 is arranged which is provided with ahan dle I08 and has the same axis as the two filters.

This handle is engaged by a tension spring IIO which is stronger thanspring I02 and tries to displace by rotation the master member I06 in ananticlockwise direction until the handle I08 comes to lie against a stopII2. At the one side of the member I06 a two-arm pawl is supportedrotatably at II6. As shown in Fig. 10, this pawl lays itself underaction of a spring II8 with a hook-shaped end I20 against thecircumference of the mounting 96. The other arm of the pawl shows anoblique surface I22. Finally another adjoined piece I24 is at thecircumference-of member I06 behind which piece, when the s utter istensioned, the hook-shaped end of a release pawl I26 subject to theaction 01 a spring I28 falls.

As shown in Fig. 11 another rotating ring I20 is arranged between thetwo filters 90, 92 and having the same axis as they, this rotating ringcarrying a projection I32 .and near it a stop I33. Projection I32engages on turning the ring (by means of a handle I34) notches I36provided'at a scale I38 at the individual graduation lines of same. Thegraduation lines of this scale designate exposure corresponding to theusual durations of exposure (e. g. /2 3 6 of a second etc.) obtained bythe known shutters. In the graduation of the scale not only the functionaccording to which the passage of light is taking place dependent on therelative motion of the filters, but also other factors influencing theaction of the shutter (e. g. lack of uniformity in the movements of thefilter OII etc.) are considered.

The action of the shutter described is as follows:

In position rest of the shutter (Fig. the position 0! filter it isdetermined by the lengthening piece Illl adjoining stop I. In this position the particles of structure of filter 90 are at right angles to theparticles of structure of the stationary filter 02 so that the passageof light through the shutter is blocked. When the'shutter is put intension member I06 is moved by means of handle I" against the force ofspring IIII away from stop I I2 in a clockwise direction, until stop Icomes to lie behind the hook of release pawl I, the master member thusbeing held firmly in its new position (Fig. 12). On reaching theposition of tension the hook-shaped end I oi the two-arm pawl movedtogether with member Ill catches besides under the action of spring IIIbehind the adjoined piece 98 of filter-mounting N. The position offilter 90 in relation to filter 02 has not been altered during theaction of tension, so that the shutter has preserved its closedposition. When the release pawl III is now moved in the direction or thearrow against the force oil-spring III, the adioined piece I is releasedand member III is displaced rotatably in an anticlockwise direction bythe shutter 'spring III. During this rotatory displacement the rotatablysupported filter II is carried along by means 0! pawl III andadioinedpiece 9! under tensioning oi spring III .(the latter beingweaker than spring III). This rotatory displacement of filter 00together with member I" lasts, until the oblique surface In of the pawlsupported at Ill buttsagainst stop I" protruding'into its path andglides along it. During this action the pawl is displaced by rotationagainst the force of its spring Hi, and thus stop 98 or thefilter-mountmg I is released (Fig. 13) Whilst master member Illcontinues now its path until handle I",

adjoins stop I I2. filter II is retracted to its original position shownin Figs. 10 and 12 in a clockwise direction by the spring I02 coming nowinto action.

as becomes apparent from the above, the position of stop I" in everycase is determining the amount 0! the rotary displacement of filter 9!.As on the other hand with polarizing filters the amount of light allowedto pass through depends according to a wellknown physical law in'everycase on the amount of the reciprocal relative movement of two filters,it is possible by adjustment of stop I by means of the handle Ill toalter at will the amount of light reaching the carrier of emulsion whenthe shutter is running down. though the speed 0! running down or theshutter always remains the same. with the example of execution describedthe notches i" of scale Itl'are amused in such a manner that during therotatory displacement or filter II adiusted thereby the same amount oflight is allowed to pass through as'with the usual durations of exposureof the known sector-shutters; these durations 0! exposure are thereforeindicated at the respective notches. although the process of opening 0!the new shutter difiers on principle from that of. the known shutters.

'In I'lga. 10, 12 and 13 the shutter or the stop Ill or samerespectively is adlustede. g. to'an amoimtotlightcorrespondinltothatatanmember I to such an extent (when the shutter runs down) that'itsparticles of structure are lying at the end of the opening movement atan acute angle to the particles or structure of the stationary filter 82(see Fig. 13).

Contrary to it Fig.-"'1'4"shows the adjustment of stop I33 to thelargest amount at light which in the present case is to correspond e. g.to that at I a period of exposure of 5 see. As may be seen from thefigure, in this instance filter SU-is separated from member Ilii only atthe end of the rotatory adjustment of the latter; with thisoper ationthe rotatory displacement of the ifilter is so large that in relation tothe structural particles of filter 92 its own structural parts come,

to lie in parallel position in which, as is known. the highest degree ofpenetrability is reached,

In the manner described all values of exposure obtained heretofore byadjustment of the period of exposure may be attained with a shutteraccording to the present invention without any alteration of the speedof the shutter-partsinoved being necessary. The device forming theobiect oi the invention may therefore be cons'tructed in a simple mannerwithout any means altering the speed (such e. g. adjustable exposureregulating mechanisms) with but one speed of running down.

With an additional arrangement on the means generally known in theconstruction oi shutters for carrying out,B- 'and T-exposures and consequently not shown indetail it is possible without difilculty with ashutter according to the invention to execute also such exposures.-

Finally it maybe mentioned that a reduction of-the'. path of rotation ofmaster member I06 and of the movement of the filter by half might beachieved by the filter 92 which with the example of execution describedis not rotata-' ble, being likewise arranged rotatable and beingcontrolled by suitable means in such a way that it moves by the sameamount as filter ill, but in opposite direction when said filter isrotatably adjusted.

The quality of a photograph may under certain conditions'strongly beinterfered with by the light of reflection occurring on smooth surfaces.

In Figs. 15 to 18 a shutter bearing the features oi the presentinvention is shown which besides the control of the passage of light mayalso be used for subduing or eliminating to the greatest possible extentthe disturbing light of refiection mentioned. As is well known, due tothe physical fact that reflected light is polarized for its greaterpart, that is that it only continues to swing in one definite plane, itis possible to subdue reflected light in general by means of apolarizing filter; therefore. all that is necessary is to rotatablydisplace a polarizing filter intercalated in the path of this light,until its structural particles lie vertical to the direction of swingingof the light whereby the latter is practically extinguished.

when. using a shutter with winch polarizing filters are serving tocontrol the light, in the usual photographic cameras with a finder or incameras with a special finder chamber it is pos= sible'to subdue andeliminate reflected light in a simple manner. All that is necessary in.such cases to support the shutter on a rotating disc at the photographiccamera, in order to be able to displace it by rotation as a whole; ithas to 15 be rotatably adjusted in every case by the same amount as apolarizing filter intercalated before the finder or the finder-lensrespectively has to be rotatably, displaced in order that its structuralparticles get into the position vertical to the swinging plane of thereflected light and thus extinguish same. By the shutters beingrotatably displaced at the same time its one filter which is not movedduring the process of exposure, gets be obtained e. g. by reading andnew adjustment of the respective amount of displacement by rotation atcorresponding scales, or also by the filter arranged in front of thefinder being coupled with the shutter (e. g. over gear-wheels) so thatsame is in every case moved along with it by the same amount at themovements of adjustment of the filter.

In consideration of the particularly simple circumstances describedabove, .showing an example of execution of a shutter for the kinds ofphotographic cameras mentioned above has been dispensed with; as anexample a shutter has been chosen that is suitable for being used withphotographic cameras with ground glass plate adjustment or with refiexcameras with joint photographic and finder lens, and with whichconsequently special means have to be provided for so as to be able toopen the shutter during the adjustment of thecamera. Such a shutter isde-- scribed hereafter under reference to the drawings.

According to Fig. 15 two disc-shaped polarizing filters I42 and I44 arearranged at corresponding axial distance and covering each other in'ashutter-casing I40, their joint middle axis I46 coinciding with theoptical axis of the photographic camera. Furthermore the arrangement ofboth filters is such that filter I42 may be rotated in relation tothecasing I 40 about the axis I46, whilst filter I44 is arrangednon-rotatable in casing I40. For the purpose of its rotatorydisplacement filter I42 is held in a ringshaped mounting I48 having twoadjoined pieces I50 and I52 at its circumference. Adjoined piece I52 isengaged by a'tension spring I54 tending to rotatingly displace mountingI48 and ter I42 in a clockwise direction until stop I52 comes to buttagainst astop I56 forming part of a rotating ring I51. having the sameaxis as the two filters; this ring carries a handle I58 and by means ofsame it may be rotatingly displaced between two stops I59 and I60.

' Furthermore a master member I6I having the same axis as the twofilters I42 and I44 is rotatably supported in casing I40 and carrying ahandle I62. This handle is engaged by a tension spring I64 of greaterforce than that of spring I54 and tends to displace rotatingly member I6| in an anticlockwise direction, until handle I62 adjoins a stop I66provided in casing I40. At the one side of member I6I a two-arm pawl isrotatably supported at I68. This pawl is formed as a hook I at its oneend and shows an oblique surface I12 at its other end. Besides a springI14 tries to rotatingly displace the pawl in a clockwise direction,which is impeded in the positions shown in Figs. and 18 by a stop pinI16 arranged in casing I 40. At the circumference of member I6I anadjolned piece I18 is providedbehind which the hook-shaped end of arelease pawl I80 places itself, when the shutter is under tension, thispawl I 80 being subject to the action of a spring I82. The release pawlmay be actuated either immediately by means of a hand lever I84 or overa wire release I86 from any desired place of the photographic camera notrepresented in de tail.

In casing I40 a hand lever I90 is rotatably supported by an axle I88which is subject to the action of a tension spring I 92. A plate springI94 fastened at the end of leve'r I90 influences a pawl I96 likewiserotatably supported by axle I88 in such a manner that it lays itselfwith its stop I98 against the one side of lever I90. The hookshaped endof pawl I96 protrudes in certain positions into the path of thelengthening piece I52 of filter mounting I48. g

The hand lever I90 penetrates through the shutter casing I40 in ahook-shaped recess I99 limited on one side of the cover plate 200 of theshutter (Fig. 17).

. position of rest shown in Fig. 16 into the acting position shown inFig. 15 or 18 handle I90 is rotatingly displaced about axle I80 from itsend position a shown in Fig. 1'1 against the action of spring I92, untilit drops into a notch 202 by its i own tension and is held there firmly(position c).

During this process pawl I96 is carried along by plate spring I94. Forthe return movement of lever I90 from this position said lever must be202; only then I pushed out by hand from notch spring I92 can enter intoaction.

Apart from the immediate operation .by hand as described the rotarydisplacement of lever I90 from its position a may also be effected by aflexible cable thrust device 204 from any desired place of thephotographic camera. The end of this fiexible cable thrust device whenactuated presses against a correspondingly formed spot of lever I90 andmoves same again towards notch 202. The path of the end of the flexiblecable thrust device is so limited, however, that lever I 90 can-' .notdrop into notch 202, but only gets as faras position b in which pawl I96is already in position of action in relation to the adjoined piece I52.From Fig. 17 it may be seen without difilculty that lever I90 is notblocked in position b so that it returns to its final position a underthe pull of spring of disengagement, when'the action of cable thrustdevice 204 has ceased.

The cases of immediate actuation of lever I90 the flexible by hand-or byusing the thrust device 204 will be explained in detail later on.

The individual parts of the shutter described above are arranged incasing I40, and according tothe invention this casing is rotatablysupported about the axis I46 at a photographic camera not represented indetail. To displace casing I40 (and with it the shutter as a whole) byrotation a handle 206 is provided. Furthermore casing I 40 carries on apart of its circumference providing about an arch-shaped plate 200 theborder of which is provided with teeth 2I0. The teeth are engaged by astationary supported spring 2I2 securing the shutter casing in itsangular position at the time against unintended rotatory displacements.On plate 208 an angle-graduation 2I4 (suitably agreeing with theindividual teeth 2l0) is provided so as to be able to fix the individualamounts of rotatory displacement also numerically.

Before describing the process of-eliminating To move pawl I96 from its-I92 without any special movement,

reflected light by the means according to the present invention, we willfirst explain the action of the means serving to execute the exposureproper.

In position of rest of the shutter (Fig. 15) the position of filter I42is determined by the lengthening piece I52 adjoining stop I00. In thisposition the structural particles of fiber I42 are at right angle to thestructural particles of filter I44 supported incapable of beingr-otatingly displaced in casing I40 so that the passage of light throughthe shutter is blocked. When the shutter is put in tension, member ISIis moved against the force of spring I04 away from stop I in a clockwisedirection, until adjoined piece I comes to lie behind the hook of therelease pawl I00 and the master member is thus firmly held in its newposition. Besides, on reaching the position of tension, the hook-shapedend I10 of the two-arm pawl supported by member ISI drops under actionof spring I14 behind the adioined piece I00 0! filter mounting I48. Theposition of filter I42 in relation to filter I44 has not been alteredduring the process of tension, so that the shutter preserved its closedposition.

when the release pawl I00 is now moved against the force of spring I02either by means of hand lever I04 or over the wire release I80 in aclockwise direction, stop I10 is released and member III is rotatinglydisplaced by spring I04 in an anticlockwise direction. By this rotatorydisplacement the rotatably supported filter I42 is carried along overpawl I10 and adioined piece I00, whilst spring I04 is tensioned (itbeing weaker than spring I04) This rotatory displacement of filter I42together with member IOI lasts, until the oblique surface I12 of thepawl supported at I00 butts against stop I10 protruding into its pathand glides along it. In doing so, the pawl is displaced rotatinglyagainst the force of its spring I14 and stop I00 of filter mounting I40is released thereby. At this moment the position of filter I42 is suchthat its structural particles lie parallel to those of filter I44, sothat the passage of light to the emulsion carrier is released. Whilstnow master member IOI comes to rest by lever I02 butting against stopI00, filter I42 is brought back to its original position shown in Fig.15 by its spring I04 and thus the passage of light through the shutteris blocked again. Whilst the exposure is executed, hand lever I90 is inthe position shown in Fig. 1 6 in which pawl I00 lies outside the .pathof lengthening piece I02, so that itcannot enter into action.

It may still be mentioned that means for regulating the speed of shutter(exposure regulating mechanism) has for reason of simplicity beenomitted in the example of execution shown.

If'now, before carrying out an exposure, a refiected light emanatingfrom a shining surface or the object of which a photograph is to betaken, is to be eliminated, this may be done e. g. with a photographiccamera with ground glass plate adjustment in the following manner:

After insertion of the ground glass plate into the photographic camerathe lever I00 is first rotatingly displaced to its notch-position 0shown in Fig. 10 and particularly in Fi n rin I01 is moved by means ofhandle 00 from its position shown in Fig. 10 into the position shown inFig. 18 as far as stop I00. By this operation also filter I42 is carriedalong over stop I00 and lengthening piece I02 against tho-force ofspring I04. Shortly before the movement of ring. I01 ends, lengtheningpiece I02 drops behind the pawl I96 protruding now into its path, sothat filter I42 is held fast in its new position. In this position,however, its structural particles lie parallel to those of filter I44fastened in casing I40, so that the sight through the shutter isunobstructed (Fig. 18). This opening of the shutter by means of handleI58 may be carried out independently from the master member IBI being inposition of rest or of tension.

Whilst looking through the ground glass plate inserted into thephotographic camera, the shut ter as a whole should be rotated by meansof the handle 200 about axis I40, until the structural particles offilter- I44 lie vertical to the swinging direction of the polarizedreflected light, this being practically extinguished thereby. Theadiusted angular position is secured by spring 2I2 engaging teeth 2I0.Then the adjustment is finished, lever I00 is again displaced rotatinglyinto its position a, pawl I00 being removed from the path of thelengthening piece I02 over stop I98. Filter I42 now moves under actionof spring I04 and carries long ring I01 back into the position shown inFig. 15, the passage of light through the shutter being blocked again.After exchanging the ground glass plate with the exposure material theexposure may now be executed in the manner previously described with theadjusted angular position or the shutter.

Fixing filter I42 in the open position shown in Fig. 18 may also beeifected by operating the flexible cable thrust device 204. During thisop eration, however, the lever I is, as described previously, displacedrotatingly only as far as position b, so that when the pressure broughtto bear on it ceases, it returns again to its original position a underaction of spring I02 and removes pawl I00 from the path of lengtheningpiece I02. Thus filter I42 is in this case held in Open position onlyduring the operation of the flexible cable thrust device 204.

The movement of pawl I00 over the device 204 is particularly suitablefor photographic cameras with a joint photographic and finder lensbecause with these apparatuses a certain erroravoiding constraint in thesequence of the various actions is rendered possible thereby. Thissequence is e. g. as follows:

If, in taking a photograph, disturbing reflected light is to beeliminated filter I42 must be rotatingly displaced into the openposition by means of handle I00. In this position the filter is heldfast readily by pawl I00, because with the last named kind ofphotographic cameras it is convenient to arrange the flexible cablethrust device 204 in such a way that it continuously tries under springpressure to hold lever I00 in position b and thus pawl I00 in actingposition. Now the open shutter can be rotatingly displaced by means ofhandle 200 into the corresponding angular position in order to eliminatethe reflected light. Before or after this adjusting movement the shuttermust be put in tension in the usual manner by means of handle I02.

After finishing the adjustment 8. release member provided at thephotographic camera is actuated. This results first of all in the device204 being pulled back from its acting position into the position ofrest, and consequently in lever I00 being brought back by spring I02from its position 0 into the original position; in doing so, filter I42is released by pawl I00 for the shutting movement. By further actuatingthe release member the swingable mirror (arranged in reflex c m ras withbut one lens) after closing the the camera lens and lastly pawl I isactuated over wire release I86, and thus the'process of exposure isbrought into effect.

From using 'the flexible cable thrust device I86 and 204 to operatemembers I80 and I00 respectively results finally with photographiccameras of any construction the advantage that the operation places maybe. arranged at will at the photographic camera, and (due to theflexibility of the thrust devices) preserve their original position whenthe shutter is rotatingly displaced.

For reasons of operation it may be advantageous with a shutter accordingto the invention to make the opening and closing movements of thepolarizing filters corresponding to a chosen variation with regard totime to execute an exposure. This may be achieved without difllculty byusing means known in the art (e. g. by inter- 'calating controllingcurves) Whatwe claim is:

1. A photographic shutter for use with a camera, said shutter comprisinga pair of shutter members formed of polarizing material, the shuttermembers being aligned with each other and being normally held in aposition wherein their axes of polarization are crossed, means formounting. said shutter members whereby they may be moved relative toeach other from said normal position to a position wherein their axes ofpolarization are parallel, and movable actuating means connected to saidshutter members for carrying out a shutter operating cycle wherein theshutter members are adjusted from said normal position to a position inwhich their axes are parallel and are then returned to said normalposition.

2 A photographic shutter carried by a camera, said shutter comprisin apair of spaced apart and aligned shutter members which are mounted forrotation about a common axis, said shutter members being formed ofpolarizing material and being normally positioned with respect to eachother to have their axes of polarization crossed, and movable actuatingmeans connected to said shutter members for carrying out a shutteroperating cycle wherein one of said shutter members is rotated from itsnormal position through 90 after which the other shutter member isrotated from its normal position and in a, similar direction through 90following which both shutter members are simultaneously returned totheir" normal position.

3. A photographic shutter mechanism carried by a camera, said shuttermechanism comprising a pair of spaced apart and aligned shutter memberswhich are mounted for rotation about a common axis, said shutter membersbeing formed of polarizing material and being normally positioned withrespect to each other to have their axes of polarization crossed,movable actuating means connected to said shutter members for carryingout a shutter operating cycle wherein one 01' said shutter members isrotated from its normal position through 90 after which the secondshutter member is rotated from its normal position and in a similardirection through 90 following which both shutter members aresimultaneously returned to their normal position and adjustable controlmeans associated with said shutter mechanism and actuated by saidoperating means for determinin the instant when the operating meansinitiates the rotation of the second shutter member from its normalposition.

4. A photographic shutter carried by a camera,

said shutter comprising a pair of spaced apart and aligned shuttermembers which are mounted for rotation about a common axis, said shuttermembers being formed of polarizing material and being normallypositioned with respect to each other to have their axes oi'polarizationcrossed,

an operating member releasably engaged with said shutter members, saidoperating member being rotatable on said axis of rotation, resilientmeans secured to the operating member and to the shutter members and toa fixed member carried by said camera; said operating member beingrotatable in one direction against the action of said spring means,releasable means for securing said operating member in a workingposition where it has been rotated against the actionof said resilientmeans, means carried by one of said shutter members when released fromengagement with said operating member and rotated for releasing thesecond shutter member from engagement therewith, and means carried bysaid second shutter member when released from engagement with theoperating member and rotated for releasing the operating member from itsworking position.

5. A camera shutter comprising a pair of spaced apart and alignedshutter members both of which are formed of polarizing material and oneofwhich is rotatable about an axis common to both of said shuttermembers, the shutter members being normally positioned with respect toeach other to have their axes of polarization crossed a and movableactuating means connected to said shutter members for carrying out ashutter operating cycle wherein the rotatable shutter member is rotatedfrom its normal position to a position wherein its polarizing axis isoriented with respect to the polarizing axis of the fixed shutter memberso that light incident to one shutter member will pass through bothshutter members after which the rotatable shutter member is returned toits normal position.

6. A camera shutter mechanism comprising a pair of spaced apart andaligned shutter members both of which are formed of polarizing materialand one of which is rotatable about an axis common to both of saidshutter members, the shutter members being normally positioned withrespect to each other to have their axes of polarization crossed,movable actuating means connected to said shutter members for carryingout a shutter operating cycle wherein the rotatable shutter member isrotated from its normal position to a position wherein its polarizingaxis is oriented with respect to the polarizing axis of the fixedshutter member so that light incident to one shutter member will passthrough both shutter members after which the rotatable shutter member isreturned to its normal position, and adjustable means carried by saidshutter mechanism for predeterminedly varying the'degree of rotationimparted to the rotatable shutter member by said actuating means wherebyto vary the time period 8. A camera shutter comprising a pair of spacedapart and aligned shutter members both of which are formed of polarizingmaterial and one or which is rotatable about an axis common to both ofsaid shutter members, the shutter members being normally positioned withrespect to each other to have their axes of polarization crossed,resilient means urging the rotatable shutter member into said normalposition, a rotatable ring member positioned between said shuttermembers and axially aligned therewith, other resilient means urging saidring member to an inoperative position whereby said ring member whenrotated to a position for operating the shutter is returned to itsinoperative position on its release from its operating position, andmeans for coupling said ring member to said rotatable shutter memberwhen th ring member is moved to its operating position and formaintaining said coupling until the ring; member has returned to itsinoperative position whereby said rotatable shutter member is moved fromits normal position on the return of the ring member to its inoperativeposition, the resilient means associated with said rotatable shuttermember returning such shutter member to its initial crossed relationwith respect to the second shutter member on the release or saidcoupling means.

9. A camera shutter as set forth in claim 8 including movably adjustablemeans for contacting and releasing said coupling means on the return ofthe ring member to its inoperative position, the position of saidadjustable means determining the degree of rotation 01 the rotatableshutter member during its coupled connection with the ring member, andrelative fixedly positioned means engageable with said adjustable meansfor retaining the adjustable means in desired position.

10. A camera shutter mechanism comprising an open-ended casing rotatablyadjustable about an axis passing through the ends thereof, a pair ofspaced apart shutter members within the easing aligned on the axis ofrotation of said casing and rotatable with the casing, one of saidshutter members being rotatable about the casing axis and the otherbeing relatively fixed with respect to said casing, both oi! saidshutter members being formed of polarizing material and being normallypositioned with respect to each other to have their axes of polarizationcrossed, movable actuating means connected to said shutter members forcarrying out a shutter operating cycle wherein the shutter member whichis rotatable relative to said casing is rotated from its normal positionto a position wherein its polarizing axis is oriented with respect tothe polarizing axis of the other shutter member so that light incidentto the relatively rotatable shutter member will pass through bothshutter members after which the relatively rotatable shutter member isreturned to its normal position, and means for retaining said casing inadjusted position.

11. A camera shutter mechanism as claimed in claim 10 having rotatableactuating means for rotating said relatively rotatable shutter member toa position where light is passed through both shutter members, saidrotatable actuating means rotating the relatively rotatable shuttermember from its normal position independentlyot the actuating means forcarrying out a shutter operating cycle and the last-named actuatingmeans returning the relatively rotatable shutter member to its normalposition from the position into which it has been independently rotated.

HANS C. DECKEL. EDUARD MAURER.

FRANZ xavan s'rommna.

